Integrated circuit structure having gate contact and method of forming same

ABSTRACT

One aspect of the disclosure relates to an integrated circuit structure. The integrated circuit structure may include: a gate stack having a gate conductor therein over a substrate, the gate stack being within a dielectric layer; a source/drain contact to a source/drain region over the substrate and adjacent to the gate stack within the dielectric layer; a conductor extending above, without contacting, the source/drain contact and extending within the dielectric layer to contact the gate conductor within the gate stack.

BACKGROUND Technical Field

The present disclosure relates to integrated circuit (IC) structures,and more particularly, to an integrated circuit structure having a gatecontact and method of forming the same.

Related Art

Advanced manufacturing of integrated circuits requires formation ofindividual circuit elements, e.g., field-effect-transistors (FETs) andthe like based on specific circuit designs. A FET generally includessource, drain, and gate terminals. The gate terminal is placed betweenthe source and drain terminals and control the current therebetween.Transistors may be formed over a substrate and may be electricallyisolated with an insulating dielectric layer, e.g., inter-leveldielectric layer. Contacts may be formed to each of the source, drain,and gate terminals through the dielectric layer in order to provide anelectrical connection between the transistors and other circuit elementsthat may be formed subsequent to the transistor in other metal levels.

A radiofrequency (RF) transistor is a device used to amplify and switchRF signals and power. As scaling down of integrated circuits continues,the RF cutoff frequency for RF transistors (f_(T)) increases while themaximum oscillation frequency (f_(max)) for the same decreases. Cutofffrequency refers to a frequency that is below which a transistor willnot operate. Put another way, cutoff frequency is the highest frequencywhich the transistor is useful in RF applications. Maximum oscillationfrequency refers to the frequency at which the maximum stable power gain(Gms) and the maximum available power gain (Gma) of a device equal 1.One parameter that reduces the maximum oscillation frequency is gateresistance. As IC structures are scaled down, gate resistance increasescausing a reduction of the maximum oscillation frequency.

FIG. 1 shows an example of a prior art IC structure 10. FIG. 2 shows across-section of IC structure 10 taken along line A-A. FIG. 3 shows across-section of IC structure 10 taken along B-B. Referring to FIGS. 1-3together, IC structure 10 may include a substrate 12 (FIGS. 1 and 3)adjacent to a shallow trench isolation (STI) region 14. A set of fins 18(FIGS. 1 and 3) may be formed form substrate 12. Substantiallysurrounding fins 18 over portions of substrate 12 and STI region 14 maybe gate stacks 20. Gate stacks 20 may include a gate conductor 22 andgate spacers 24.

IC structure 10 may also include source/drain contacts 28 (FIGS. 1 and3) overlying portions of fins 18 to provide electrical connection tosource/drain regions (not shown) therein. Source/drain contacts 28 maybe adjacent to gate stacks 20 over substrate 12 and STI region 14. ICstructure 10 may also include a gate contact 32. Gate contact 32provides electrical connection to gate stacks 20. IC structure 10 mayalso include a dielectric layer 36 over substrate 12 and STI region 14.Dielectric layer 36 may substantially surround fins 18, gate stacks 20,source/drain contacts 28, and gate contact 32. In FIG. 1, dielectriclayer 36 is shown by phantom box in order to show features of ICstructure 10 thereunder. Further, IC structure 10 may also include oneor more contacts 38 to source/drain contacts 28. Contacts 38 may bedisposed within dielectric layer 36 in the same plane as gate contact32. Contacts 38 provide electrical connection from source/drain contacts28 to other structures and devices that may be formed in metal levelsabove dielectric layer 36.

Conventional gate contacts 32 are formed over gate stacks 20 over STIregion 14 and not over gate stacks 20 in the active region, or oversubstrate 12. Forming gate contacts 32 over STI region 14 results in ahigh gate resistance. Gate resistance is dependent in part on the lengthof gate stacks 20 and the distance of gate contact 32 to each end ofgate stacks 20. When gate contacts 32 are formed over STI region 14,gate contacts 32 are closer to one end of gate stacks 32 than the other.Thus, an increase in gate resistance reduces the maximum oscillationfrequency and RF cutoff frequency increases.

SUMMARY

A first aspect of the disclosure provides for a method of forming anintegrated circuit structure. The method may include: lowering a heightof a source/drain contact within a first dielectric layer to a heightbelow a height of a gate conductor of a gate stack, the gate stack beingadjacent to the gate conductor within the dielectric layer; and forminga conductor over and without contacting the source/drain contact, theconductor contacting the gate conductor.

A second aspect of the disclosure provides for a method of forming andintegrated circuit structure. The method may include: lowering a heightof one or more source/drain contacts in a set of source/drain contactsbelow a height of a gate conductor within a gate stack of a set of gatestacks, the one or more source/drain contacts in the set of source/draincontacts being adjacent to the gate stack of the set of gate stackswithin a first dielectric layer; and forming a conductor over andwithout contacting the set of source/drain contacts, the conductorcontacting each gate conductor.

A third aspect of the disclosure provides for an integrated circuitstructure. The integrated circuit structure may include: a gate stackhaving a gate conductor therein over a substrate, the gate stack beingwithin a dielectric layer; a source/drain contact to a source/drainregion over the substrate and adjacent to the gate stack within thedielectric layer; a conductor extending above, without contacting, thesource/drain contact and extending within the dielectric layer tocontact the gate conductor within the gate stack.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this disclosure will be more readilyunderstood from the following detailed description of the variousaspects of the disclosure taken in conjunction with the accompanyingdrawings that depict various embodiments of the disclosure, in which:

FIG. 1 shows a top-down view of a prior art integrated circuit (IC)structure.

FIG. 2 shows a cross-section of the prior art IC structure of FIG. 1taken along line A-A.

FIG. 3 shows a cross-section of the prior art IC structure of FIG. 1taken along line B-B.

FIGS. 4-9 show a cross-section of a preliminary IC structure undergoingaspects of a method according to embodiments of the disclosure with FIG.9 showing a resulting IC structure.

FIG. 10 shows a top-down view of an IC structure according to anembodiment of the disclosure.

FIG. 11 shows a cross-section of the IC structure of FIG. 10 taken alongline D-D.

FIG. 12 shows a top-down view of an IC structure according to anembodiment of the disclosure.

FIG. 13 shows a cross-section of the IC structure of FIG. 12 taken alongline F-F.

It is noted that the drawings of the disclosure are not to scale. Thedrawings are intended to depict only typical aspects of the invention,and therefore should not be considered as limiting the scope of theinvention. In the drawings, like numbering represents like elementsbetween the drawings.

DETAILED DESCRIPTION

The present disclosure relates to an integrated circuit (IC) structure,and more particularly, to an integrated circuit structure having a gatecontact and method of forming the same. Embodiments discussed hereinprovide a method of forming, and a corresponding structure, for aradiofrequency (RF) transistor having a reduced gate resistance. The ICstructure as described herein includes a gate contact within the activeregion of the IC structure which causes a reduction in gate resistance.With the gate contact being located within active region, the gatecontact is closer to each end of the gate stack than conventional gatecontacts that are located over the STI region. The reduction of the gateresistance results in an increase in the maximum oscillation frequency(f_(max)) and a decrease in RF cutoff frequency (f_(T)).

FIGS. 4-9 show a cross-section of a preliminary IC structure undergoingaspects of a method according to embodiments of the disclosure, withFIG. 9 showing a resulting IC structure. Referring now to FIG. 4, apreliminary IC structure 100 is shown. IC structure 100 may be afin-shaped field effect transistor (finFET) as shown. IC structure 100may include a substrate 102 from which a fin 106 may be formed such thatfin 106 is over substrate 102. In some embodiments, substrate 102 mayinclude a semiconductor-on-insulator (SOI) substrate. In such anembodiment, substrate 102 may include a semiconductor layer, aninsulator layer overlying the semiconductor layer, and anothersemiconductor layer overlying the insulator layer. An SOI substrate maybe formed by depositing the insulator layer over the semiconductor layerand depositing another semiconductor layer over the insulator layer. Thesemiconductor layers may each include but are not limited to silicon,germanium, silicon germanium, silicon carbide, and those consistingessentially of one or more III-V compound semiconductors having acomposition defined by the formulaAl_(X1)Ga_(X2)In_(X3)As_(Y1)P_(Y2)N_(Y3)Sb_(Y4), where X1, X2, X3, Y1,Y2, Y3, and Y4 represent relative proportions, each greater than orequal to zero and X1+X2+X3+Y1+Y2+Y3+Y4=1 (1 being the total relativemole quantity). Other suitable substrates include II-VI compoundsemiconductors having a composition Zn_(A1)Cd_(A2)Se_(B1)Te_(B2), whereA1, A2, B1, and B2 are relative proportions each greater than or equalto zero and A1+A2+B1+B2=1 (1 being a total mole quantity). The insulatorlayer may include silicon oxide (BOX layer) or other inorganicdielectric materials.

A shallow trench isolation (STI) region (not shown in FIG. 1) may bedisposed adjacent to substrate 102 as will be described herein. As knownin the art, STI regions separate or isolate adjacent semiconductordevices that are on the same plane from one another. STI regions preventelectrical current leakage from the adjacent semiconductor devices. STIregions typically include an insulator, such as, for example, silicondioxide. STI regions may be formed by etching portions of substrate 102to form trenches therein, and filling the trenches, e.g., viadepositing, with the insulator.

As used herein, the term “depositing” may include any now known or laterdeveloped technique appropriate for deposition, including but notlimited to, for example: chemical vapor deposition (CVD), low-pressureCVD (LPCVD), plasma-enhanced CVD (PECVD), semi-atmosphere CVD (SACVD)high density plasma CVD (HDPCVD), rapid thermal CVD (RTCVD), ultra-highvacuum CVD (UHVCVD), limited reaction processing CVD (LRPCVD),metalorganic CVD (MOCVD), sputtering deposition, ion beam deposition,electron beam deposition, laser assisted deposition, thermal oxidation,thermal nitridation, spin-on methods, physical vapor deposition (PVD),atomic layer deposition (ALD), chemical oxidation, molecular beamepitaxy (MBE), plating, and evaporation.

Fin 106 maybe patterned and etched from the semiconductor layeroverlying the insulator layer as is known in the art. In anotherembodiment, substrate 102 may include a bulk silicon substrate fromwhich fin 106 may be patterned and etched as is known in the art. WhileIC structure 100 is shown and described as a finFET, it is to beunderstood that IC structure 100 may be any other type of transistor,e.g., a planar transistor, without departing from aspects of thedisclosure.

“Etching” generally refers to the removal of material from a substrateor structures formed on the substrate by wet or dry chemical means. Insome instances, it may be desirable to selectively remove material fromcertain areas of the substrate. In such an instance, a mask may be usedto prevent the removal of material from certain areas of the substrate.There are generally two categories of etching, (i) wet etch and (ii) dryetch. Wet etching may be used to selectively dissolve a given materialand leave another material relatively intact. Wet etching is typicallyperformed with a solvent, such as an acid. Dry etching may be performedusing a plasma which may produce energetic free radicals, or speciesneutrally charged, that react or impinge at the surface of the wafer.Neutral particles may attack the wafer from all angles, and thus, thisprocess is isotropic. Ion milling, or sputter etching, bombards thewafer with energetic ions of noble gases from a single direction, andthus, this process is highly anisotropic. A reactive-ion etch (RIE)operates under conditions intermediate between sputter etching andplasma etching and may be used to produce deep, narrow features, such astrenches.

Conventional device processing may continue by forming gate stacks 110and source/drain regions 112 in, on, and/or surrounding fin 106 as knownin the art. Gate stacks 110 may substantially surround fin 106 oversubstrate 102. While four gate stacks have been shown, any number ofgate stacks may be formed over fin 106 without departing from aspects ofthe disclosure. Gate stacks 110 may each include a gate conductor 116and gate spacers 118 substantially surrounding gate conductor 116. Gateconductor 116 may include, for example, titanium, titanium nitride,tungsten, tungsten nitride, copper, copper nitride, tantalum, ortantalum nitride. While not shown herein, it is to be understood thatgate stacks 110 may also include a gate dielectric (not shown) and workfunction metal layers (not shown) between fin 106 and gate conductor116. Further, overlying gate conductor 116 may be a gate cap layer (notshown). The gate dielectric may include, for example, at least one of:hafnium oxide, hafnium silicate, nitride hafnium silicate, zirconiumoxide, zirconium silicate, titanium oxide, lanthanum oxide, yttriumoxide, aluminum oxide, or combinations thereof. The work function metallayers may act as a doping source, and a different work function settingmetal can then be employed depending on whether an n-typefield-effect-transistor (NFET) or a p-type field-effect-transistor(PFET) device is desired. Thus, the same gate conductor can be used ineach of the devices, yet a different (if so desired) work functionsetting metal can be used in one or more devices to obtain a differentdoping polarity. By way of example only, suitable work function settingmetals for use in PFET devices include, but are not limited to aluminum,dysprosium, gadolinium, and ytterbium. Suitable work function settingmetals for use in NFET devices include, but are not limited tolanthanum, titanium, and tantalum. The gate cap layer may include, forexample, at least one of: an oxide, e.g., silicon dioxide, or a nitride,e.g., silicon nitride. Gate spacers 118 may include, for example, atleast one of: an oxide, e.g., silicon dioxide, or a nitride, e.g.,silicon nitride.

After gate stack 110 formation, source/drain regions 112 may be formedfrom exposed portions of fins 106, e.g., between gate stacks 110.Source/drain regions 112 may be formed by doping, depositing, and/orepitaxial growth of semiconducting material on or around fins 106. Forexample, source/drain regions 112 may be formed by implanting n-type orp-type dopants directly into fin 106. In another example, source/drainregions 112 may be formed by growth of an epitaxial material 172 fromfins 106 such that epitaxial material 172 surrounds fins 106 as shown inthe cross-sectional views of FIGS. 11 and 13. Epitaxial material 172 maybe chosen dependent on whether a PFET or an NFET is desired. In oneexample, where an NEFT is desired, silicon may be epitaxially grown andsubsequently doped with an n-type dopant, e.g., carbon, such thatepitaxial material includes carbon-doped silicon. In another example,where a PFET is desired, silicon germanium may be epitaxially grown andsubsequently doped with a p-type dopant, e.g., boron, such thatepitaxial material includes boron-doped silicon germanium.

The terms “epitaxial growth and/or deposition” and “epitaxially formedand/or grown” mean the growth of a semiconductor material on adeposition surface of a semiconductor material, in which thesemiconductor material being grown may have the same crystallinecharacteristics as the semiconductor material of the deposition surface.In an epitaxial deposition process, the chemical reactants provided bythe source gases are controlled and the system parameters are set sothat the depositing atoms arrive at the deposition surface of thesemiconductor substrate with sufficient energy to move around on thesurface and orient themselves to the crystal arrangement of the atoms ofthe deposition surface. Therefore, an epitaxial semiconductor materialmay have the same crystalline characteristics as the deposition surfaceon which it may be formed. For example, an epitaxial semiconductormaterial deposited on a {100} crystal surface may take on a {100}orientation. In some embodiments, epitaxial growth and/or depositionprocesses may be selective to forming on semiconductor surfaces, and maynot deposit material on dielectric surfaces, such as silicon dioxide orsilicon nitride surfaces.

IC structure 100 may also include a dielectric layer 122 over fin 106(including any epitaxial material surrounding fin 106) and substantiallysurrounding gate stacks 110. Dielectric layer 122 may include, forexample, silicon nitride, silicon oxide, fluorinated SiO₂ (FSG),hydrogenated silicon oxycarbide (SiCOH), porous SiCOH,boro-phospho-silicate glass (BPSG), silsesquioxanes, carbon doped oxides(i.e., organosilicates) that include atoms of silicon, carbon, oxygen,and/or hydrogen, thermosetting polyarylene ethers, SiLK (a polyaryleneether available from Dow Chemical Corporation), a spin-on silicon-carboncontaining polymer material available from JSR Corporation, other lowdielectric constant (<3.9) material, or layers thereof. Dielectric layer122 may be formed by deposition of dielectric layer material.

IC structure 100 may also include source/drain contacts 124.Source/drain contacts 124 may be formed by forming a mask (not shown),patterning the mask, and etching an opening (not shown) withindielectric layer 122 to expose source/drain regions 112 of fin 106(including any source/drain region 112 formed from any epitaxialmaterial surrounding fin 106). Source/drain contacts 124 may be formedwithin the opening. Source/drain contacts 124 may contact source/drainregion 112 and provide electrical connect thereto. Source/drain contacts124 may be formed by depositing a liner layer, e.g., titanium, and ametallization layer within the opening to fill the opening. Further, theprocess may include annealing source/drain regions 112 at the bottom ofthe opening to create a silicide (not shown) therein, i.e., siliconmetal alloy, thereby creating a surface for the contact connection. Thesilicide that is formed in aforementioned manner may be called linersilicide. Source/drain contact 124 may be planarized to a top surface ofdielectric layer 122.

Planarization refers to various processes that make a surface moreplanar (that is, more flat and/or smooth). Chemical-mechanical-polishing(CMP) is one currently conventional planarization process whichplanarizes surfaces with a combination of chemical reactions andmechanical forces.

Other currently conventional planarization techniques may include: (i)oxidation; (ii) chemical etching; (iii) taper control by ion implantdamage; (iv) deposition of films of low-melting point glass; (v)resputtering of deposited films to smooth them out; (vi) photosensitivepolyimide (PSPI) films; (vii) new resins; (viii) low-viscosity liquidepoxies; (ix) spin-on glass (SOG) materials; and/or (x) sacrificialetch-back.

A “mask” is a material or stack of materials which may be formed over anunderlying material which is to be processed. The mask may be patternedto have openings such that the underlying material is exposed.Subsequently, the underlying material may be processed where theunderlying material is exposed by the openings in the mask. Once theunderlying material is processed, the mask may be removed. Conventionalmasking materials include photoresist, silicon oxide, amorphous carbon,spin-on materials and silicon nitride.

Referring now to FIG. 5, source/drain contacts 124 may be recessed tocreate openings 128 within dielectric layer 122 over source/draincontacts 124. That is, a height of source/drain contacts 124 may belowered to a height that is below a height of gate conductor 116 of eachgate stack 110. Source/drain contacts 124 may be recessed by etching,e.g., RIE. Source/drain contacts 124 may be etched such that a portionof source/drain contacts 124 remain over source/drain regions 112 withinfin 106. Turning to FIG. 6, an insulating layer 132 may be formed withinopenings 128 over the recessed source/drain contacts 124. Insulatinglayer 132 may include a layer having a low dielectric constant (low-kdielectric layer). Low-k dielectric layer may include, for example,silicon nitride, silicon oxide, fluorinated SiO₂ (FSG), hydrogenatedsilicon oxycarbide (SiCOH), porous SiCOH, boro-phospho-silicate glass(BPSG), silsesquioxanes, carbon doped oxides (i.e., organosilicates)that include atoms of silicon, carbon, oxygen, and/or hydrogen,thermosetting polyarylene ethers, SiLK (a polyarylene ether availablefrom Dow Chemical Corporation), a spin-on silicon-carbon containingpolymer material available from JSR Corporation, other low dielectricconstant (<3.9) material, or layers thereof insulating layer 132 maythen be formed by depositing insulating layer material within opening(s)128 and planarizing the insulating layer material to a top surface ofdielectric layer 122.

Referring now to FIG. 7, another dielectric layer 136 may be formed,e.g., deposited, over dielectric layer 122 and insulating layer 132.Dielectric layer 136 may include any of the materials discussed withrespect to dielectric layer 122 such that dielectric layer 136 anddielectric layer 122 may, in one instance, be of the same material orcomposition. Further, a mask 138 may be formed, e.g., deposited, overdielectric layer 136. Mask 138 may be patterned and etched to expose aportion of dielectric layer 136 where it is desired for dielectric layer136 to be etched.

As shown in FIG. 8, the exposed portions of dielectric layer 136 may beremoved, e.g., via etching (RIE). The etching may continue throughdielectric layer 122 until top portions of gate conductor 116 of anyunderlying gate stack 110 are exposed by an opening 142. Opening 142 mayalso expose portions of insulating layer 132. In an embodiment wherethere is a gate cap layer (not shown) over gate conductor 116, the gatecap layer may also be removed, e.g., via etching, to expose gateconductor 116 thereunder.

Referring now to FIG. 9, a conductor 146 may be formed within opening142 such that conductor 146 is formed over, and without contacting,source/drain contacts 124. Conductor 146 may be formed such thatconductor 146 contacts gate conductor 116 and portions of low-kdielectric layer 132. Conductor 146 may be a gate contact providingelectrical connection to gate stacks 110 thereunder. Conductor 146 mayinclude, for example, tungsten, cobalt, or copper. Conductor 146 may beplanarized to a top surface of dielectric layer 136. The resulting ICstructure 190 after planarization may include gate stack 110 having gateconductor 116 therein over substrate 102. Gate stack 110 may be withindielectric layer 122. IC structure 190 may also include source/draincontact 124 to a source/drain region 112 over substrate 102 and adjacentto gate stack 110 within dielectric layer 122. Further, insulating layer132 may be disposed within opening 128 (FIGS. 2-3) over source/draincontact 124 within dielectric layer 122 and separate source/draincontact 124 and conductor 146. In some embodiments, portions ofinsulating layer 132 may be disposed within dielectric layer 136.Conductor 146 may extend over at least a portion of the insulating layer132 and extend within portions of dielectric layers 122, 136 to contactgate conductor 116 within the gate stack 110.

It is to be understood that processes of the disclosure as describedherein may be customized based on desired application of IC structure190. That is, the forming the patterning and etching of mask 138 (FIG.7) to form opening 142 (FIGS. 8-9) may be customized and/or modified toresult in opening 142 having any desired configuration to exposeportions of gate conductors 116 of gate stacks 110 and low-k dielectriclayers 132 thereunder.

For example, FIG. 10 shows a top-down view of IC structure 190 accordingto one embodiment of the disclosure wherein the embodiments describedwith respect to FIGS. 4-9 show cross-sections taken along line C-C ofFIG. 10. FIG. 11 shows a cross-section of IC structure 190 taken alongline D-D of FIG. 10. Further, dielectric layers 122, 136 are shown as aphantom box in FIG. 10 such that features of IC structure 190 thereundercan be seen.

Turning now to FIGS. 10-11, conductor 146 may be formed withindielectric layers 122, 136 over one or more gate stacks 110 (FIG. 10)and low-k dielectric layer 132 substantially within the active region ofIC structure 190, or over substrate 102, as opposed to substantiallyover STI region 156 that is adjacent to substrate 102. That is,conductor 146 formed herein is closer to each end of gate stacks 110than conventional gate contacts over STI region 156. Such a featureresults in a reduction of gate resistance and an increase in the maximumoscillation frequency.

As shown in FIGS. 10-11, source/drain contacts 124 may contact epitaxialmaterial 172 surrounding fin 106. However, in other embodiments,source/drain contact 124 may contact fin 106 directly where fin 106 wasdoped to form source/drain regions 112 (FIG. 9) within fin 106. Further,a portion of source/drain contact 124 over STI region 156 may not havebeen recessed as was described with respect to FIG. 5. In such anembodiment, the lithographic process used to recess source/drain contact124 may include covering portions of source/drain contact 124 over STIregion 156 with the mask such that the portions of source/drain contact124 over STI region 156 are not etched or recessed. The portions ofsource/drain contact 124 over STI region 156 may extend from withindielectric layer 122 to a top surface of dielectric layer 122 such thata top surface of those portions of source/drain contact 124 aresubstantially planar with a top surface of low-k dielectric layer 132that is over the portions of the recessed source/drain contact 124.

In further embodiments, it may be desirable to form contacts 160 tosource/drain contacts 124 to provide electrical connection fromsource/drain contacts 124 to metal levels that may be formed abovedielectric layer 136. Contacts 160 may be formed over the portions ofsource/drain contact 124 that was not recessed, or portions ofsource/drain contact 124 over STI region 156. Contacts 160 may be formedwithin dielectric layer 136 such that contacts 160 are within the sameplane as conductor 146. Contacts 160 may formed within dielectric layer136 by conventional lithographic techniques, e.g., masking, patterning,etching, depositing, and planarizing. Contacts 160 may include aconductive metal such as any of the conductive metals discussed hereinand may be formed simultaneously with the formation of conductor 146. Inother embodiments, contacts 160 may be formed before or after theformation of conductor 146.

FIGS. 12-13 show another example of IC structure 190 according toembodiments of the disclosure. FIG. 12 shows a top-down view of ICstructure 190 according to one embodiment of the disclosure wherein theembodiments described with respect to FIGS. 4-9 show cross-sectionstaken along line E-E of FIG. 12. FIG. 13 shows a cross-section of ICstructure 190 taken along line F-F of FIG. 12. Further, dielectriclayers 122, 136 are shown as a phantom box in FIG. 12 such that featuresof IC structure 190 thereunder can be seen.

Turning now to FIGS. 12-13, conductor 146 may be formed withindielectric layers 122, 136 over one or more gate stacks 110 (FIG. 12)and over low-k dielectric layer 132 substantially within the activeregion of IC structure 190, or over substrate 102, as opposed tosubstantially over STI region 156 that is adjacent to substrate 102.Such a feature results in a reduction of gate resistance and an increasein the maximum oscillation frequency.

As shown in FIGS. 12-13, a portion of source/drain contact 124 maycontact epitaxial material 172 surrounding fin 106. However, in otherembodiments, source/drain contact 124 may contact fin 106 directly wherefin 106 was doped to form source/drain regions 112 (FIG. 9) within fin106. Further, a portion of source/drain contact 124 over STI region 156may not have been recessed as was described with respect to FIG. 5. Insuch an embodiment, the lithographic process used to recess source/draincontact 124 may include covering portions of source/drain contact 124over STI region 156 with the mask such that the portions of source/draincontact 124 over STI region 156 are not etched or recessed. The portionsof source/drain contact 124 over STI region 156 may extend from withindielectric layer 122 to a top surface of dielectric layer 122 such thata top surface of those portions of source/drain contact 124 aresubstantially planar with a top surface of low-k dielectric layer 132that is over the portions of the recessed source/drain contact 124. Insome embodiments (shown), the unrecessed portion of source/drain contact124 may straddle a portion of substrate 102 and STI region 156. Thisembodiment may differ from the embodiment shown in FIGS. 10-11 in thatconductor 146 has a width W1 (FIG. 12) that is substantially smallerthan a width W2 (FIG. 10) of conductor 146 described with respect toFIGS. 10-11.

In further embodiments, it may be desirable to form contacts 160 tosource/drain contacts 124 to provide electrical connection fromsource/drain contacts to metal levels that may be formed abovedielectric layer 136. Contacts 160 may be formed over the portions ofsource/drain contact 124 that was not recessed, or portions ofsource/drain contact 124 over STI region 156. Contacts 160 may be formedwithin dielectric layer 136 such that contacts 160 are within the sameplane as conductor 146. Contacts 160 may formed within dielectric layer136 by conventional lithographic techniques, e.g., masking, patterning,etching, depositing, and planarizing. Contacts 160 may include aconductive metal such as any of the conductive metals discussed hereinand may be formed simultaneously with the formation of conductor 146. Inother embodiments, contacts 160 may be formed before or after theformation of conductor 146.

The methods as described above are used in the fabrication of integratedcircuit chips. The resulting integrated circuit chips can be distributedby the fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. “Optional” or “optionally” means thatthe subsequently described event or circumstance may or may not occur,and that the description includes instances where the event occurs andinstances where it does not.

The descriptions of the various embodiments of the present disclosurehave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

We claim:
 1. A method of forming an integrated circuit structure, themethod comprising: reducing a height of a source/drain contact within afirst dielectric layer from an initial height above a substrate to areduced height, the reduced height being less than a height above thesubstrate of a gate conductor of a gate stack, the gate stack beingadjacent to the gate conductor within the dielectric layer, wherein theinitial height of the source/drain contact is greater than the height ofthe gate conductor; and forming an upper conductor over and withoutcontacting the source/drain contact, the upper conductor contacting thegate conductor.
 2. The method of claim 1, wherein the reducing theheight of the source/drain contact includes: recessing a portion of thesource/drain contact within the first dielectric layer to create a firstopening in the first dielectric layer over the recessed portion of thesource/drain contact; and forming an insulator layer over the recessedportion of the source/drain contact within the first opening wherein theinsulator layer electrically isolates the source/drain contact from theupper conductor.
 3. The method of claim 2, wherein forming the insulatorlayer includes forming a low-k dielectric layer over the recessedportion of the source/drain contact within the first opening.
 4. Themethod of claim 2, wherein recessing the portion of the source/draincontact includes recessing the portion of the source/drain contact suchthat the portion of the source/drain contact remains within the firstdielectric layer over a source/drain region.
 5. The method of claim 2,wherein forming the conductor includes: after the forming of theinsulating layer, forming a second dielectric layer over the firstdielectric layer and the insulating layer; forming a second openingwithin the second dielectric layer over the insulating layer to exposethe insulating layer; and forming the conductor within the secondopening over the exposed insulating layer.
 6. The method of claim 5,further comprising: after the forming of the insulating layer and priorto the forming of the second dielectric layer, planarizing theinsulating layer to a top surface of the first dielectric layer.
 7. Themethod of claim 5, wherein forming the second opening includes exposinga top surface of the gate conductor within the gate stack.
 8. The methodof claim 1, further comprising: forming a contact to an unrecessedportion of the source/drain contact, the unrecessed portion of thesource/drain contact being over a shallow-trench isolation (STI) region.9. The method of claim 1, wherein the initial height of the source/draincontact is substantially co-planar with an upper surface of the firstdielectric layer.
 10. A method of forming an integrated circuitstructure, the method comprising: reducing a height of one or moresource/drain contacts in a set of source/drain contacts from an initialheight above a substrate to a reduced height, the reduced height beingless than a height above the substrate of a gate conductor within a gatestack of a set of gate stacks, the one or more source/drain contacts inthe set of source/drain contacts being adjacent to the gate stack of theset of gate stacks within a first dielectric layer, wherein the initialheight of the one or more source/drain contacts is greater than theheight of the gate conductor; and forming an upper conductor over andwithout contacting the set of source/drain contacts, the upper conductorcontacting each gate conductor.
 11. The method of claim 10, wherein thereducing the height of the one or more source/drain contacts includes:recessing a portion of the one or more source/drain contacts within thefirst dielectric layer to create a first opening in the first dielectriclayer over the recessed portion of the one or more source/draincontacts; and forming an insulator layer over the recessed portion ofthe one or more source/drain contacts within the first opening whereinthe insulator layer electrically isolates the one or more source/draincontacts from the upper conductor.
 12. The method of claim 11, whereinforming the insulator layer includes forming a low-k dielectric layerover the recessed portion of the one or more source/drain contactswithin the first opening.
 13. The method of claim 11, wherein recessingthe portion of the one or more source/drain contacts includes recessingthe portion of the one or more source/drain contacts such that theportion of one or more source/drain contacts remains within the firstdielectric layer over a source/drain region.
 14. The method of claim 11,wherein forming the conductor includes: after forming the insulatinglayer, forming a second dielectric layer over the first dielectric layerand the insulating layer; forming a second opening within the seconddielectric layer over the insulating layer to expose the insulatinglayer; forming the conductor within the second opening over the exposedinsulating layer.
 15. The method of claim 14, further comprising: afterthe forming of the insulating layer and prior to the forming of thesecond dielectric layer, planarizing the insulating layer to a topsurface of the first dielectric layer.
 16. The method of claim 14,wherein forming the second opening includes exposing a top surface ofthe gate conductor within one or more gate stacks in the set of gatestacks.
 17. The method of claim 10, wherein the initial height of theone or more source/drain contacts in the set of source/drain contacts issubstantially co-planar with an upper surface of the first dielectriclayer.